In various medical applications an implanted catheter is needed to access a patient's circulatory system. The implanted catheter may be utilized, for example, for delivery of medication/fluids or retrieval/sampling of blood. For example, it may be desirable to establish a central line (i.e., access to a large vein) for infusion of medications, chemotherapy drugs, antibiotics, anti-nausea medications, blood products, nutrients or fluids. Implanted catheters are also used in dialysis, apheresis, and other applications requiring diversion of a part of the blood flow in the circulatory system for processing or filtering. However, a common problem associated with implanted catheters is the increased risk of infection due to the establishment of this artificial path into the patient's body. The risk of infection increases the longer the catheter remains implanted.
One common approach to decrease the risk of infection is to “tunnel” the proximal end (i.e., the physician access end) of the catheter within the patient's body such that the catheter enters the body at a location that is displaced from the location where the catheter enters a major blood vessel within the patient's body. For example, a central line may be established by inserting a catheter into the subclavian vein that runs behind the clavicle, but the catheter entry point into the patient's body may be moved away from an area next to the clavicle to an area that is not immediately above the entry point into the subclavian vein. In this process, the actual access to the subclavian vein is still achieved by a puncture under the clavicle, but the proximal portion of the catheter is pulled under the skin for about 2-4 inches and emerges from the body at a location close to the nipple. This procedure may allow the catheter to stay in place for weeks to months, or even, in some circumstances, for years.
A tunneler may be utilized to assist in the tunneling of a catheter from a surface entry location on the patient's body to a location where the catheter actually enters a vessel into the circulatory system. Such a tunneler is generally made of steel or hard plastic and has a tapered distal end for tunneling through bodily tissue. Typically, the proximal end of the tunneler has a barb for insertion into the lumen of the catheter. An oversleeve is then typically forced onto the portion of the catheter that has been expanded by the barb. In one application, the catheter placement is accomplished by first making a cut-down incision near the neck of the patient, and then making an exit site incision remote from the cut-down incision. The catheter is attached to the tunneler by forcing the proximal barbed end thereof into the lumen of the catheter and sliding a sleeve over the catheter. A sleeve with a larger outer diameter may be used so that when the tunnel is made, the hole created is sufficiently large to prevent constricting forces from acting on the catheter as it resides in the tunnel. The tunneler with catheter attached is then pushed from the exit site incision toward the cut-down incision, creating a subcutaneous tunnel. When the tip of the tunneler emerges at the cut-down site, it is grasped by the physician, who pulls it through until reaching the sleeve on the tunneler. The sleeve is then pushed off the catheter and the proximal end of the tunneler is pulled out from the catheter lumen. The catheter distal end is then placed into the blood vessel.
Examples of various tunneling and gripping devices are disclosed in U.S. Patent Application Pub. No. US 2004/0006329 A1, titled “DEVICE FOR HOLDING AND GUIDING A GUIDE-WIRE IN A CATHETER” by Scheu, published Jan. 8, 2004; U.S. Patent Application Pub. No. US 2004/0039372 A1, titled “OVER-THE-WIRE CATHETER HAVING A SLIDABLE INSTRUCMENT FOR GRIPPING A GUIDE-WIRE” by Carmody, published Feb. 26, 2004; U.S. Pat. No. 3,724,882, titled “TUBE-TO-HOSE CONNECTION” issued to Dehar, dated Apr. 3, 1973; U.S. Pat. No. 4,143,893, titled “CLAMPING DEVICE” issued to Fleischer, dated Mar. 13, 1979; U.S. Pat. No. 4,672,979, titled “SUTURE SLEEVE ASSEMBLY” issued to Pohndorf, dated Jun. 16, 1987; U.S. Pat. No. 5,306,240, titled “TUNNELER AND METHOD FOR IMPLANTING SUBCUTANEOUS VASCULAR ACCESS GRAFTS” issued to Berry, dated Apr. 26, 1994; U.S. Pat. No. 5,405,329, titled “INTRAVASCULAR MULTI-LUMEN CATHETER, CAPABLE OF BEING IMPLANTED BY “TUNNELING” issued to Durand, dated Apr. 11, 1995; and U.S. Pat. No. 6,475,244 B2, titled “TUNNELING DEVICE” issued to Herweck et al., dated Nov. 5, 2002; each of which is incorporated herein by reference in its entirety.
One of the disadvantages of the current tunneling devices is that attachment and removal of the barbed end of the tunneler from the lumen of the catheter often results in damage to the lumen and the distal tip of the catheter. Typically, the barb is much larger than the diameter of the catheter lumen and thus forces the tip of the catheter to expand radially and makes the tip prone to damage. Moreover, with respect to the typical use of an oversleeve, the axial motion along the length of the tunneler, which pushes the oversleeve onto the expanded catheter over the barb or pulls the oversleeve off the expanded catheter over the barb, may cause significant abrasion on the exterior of the catheter body. In addition, such lateral grinding of the oversleeve onto the catheter over the barb may cause tearing of the catheter body.
Thus, an improved tunneler capable of securing a catheter at the proximal end of the tunneler without tearing the body or damaging the tip of the catheter may be desired. In particular, it may be desirable to minimize the abrasion caused by the lateral movement of the oversleeve, which can damage the outer circumferential surface of the catheter and compromises the integrity of the catheter body.